Epoch Converter

Seconds, milliseconds, or a date string

A value made only of digits is treated as a Unix timestamp. If it has 13 or more digits, it is milliseconds. Shorter digit strings are seconds, and they are multiplied by 1000 before a date is built. The number 0 is the epoch itself. A decimal such as 1.5 is allowed for the seconds path. Anything else is handed to the date parser as a date string, which accepts an ISO string and other text the browser can parse. An empty box stops with Enter a Unix timestamp or ISO date. A digit string that cannot become a real date stops with Invalid Unix timestamp. Other unreadable text stops with Invalid date string.

Five lines, one of them local

A successful run prints five lines. ISO 8601 is the UTC instant ending in Z. UTC is the English GMT line. Local uses the timezone of the computer you are on, so two people can paste the same number and see different local lines. Unix seconds are the instant floored to a whole second. Unix milliseconds are the same instant in ms. For input 0 the ISO line is 1970-01-01T00:00:00.000Z, Unix seconds are 0, and Unix milliseconds are 0. The local line that day depends on your offset from UTC. This page does not convert a timezone name by itself. It does not add or subtract a duration.

What the digit count changes

1700000000 has 10 digits, so it is seconds. 1700000000000 has 13 digits, so it is milliseconds. Mixing those up moves the result by centuries. A timestamp in microseconds is not detected. Paste seconds or milliseconds only. Negative numbers fail the digit test and fall through to the date parser, which will not treat them as Unix time. A leading plus sign also fails the digit test. If you already have a calendar date and want the number, paste the date string and read the Unix lines. Date Difference is for the span between two dates. This box holds one value.

What this is not

There is no live clock and no countdown. Countdown tools are separate. Week numbers are a separate page. A cron expression is not a timestamp. If the local line surprises you, check the computer timezone before you blame the number. The ISO line is the one that stays the same across machines. Copy that line when you need to share an instant. The conversion stays on this device. Nothing about the timestamp is stored.